Heat exchangers using an impingement cooling principal are known for exchanging heat between different fluids flowing through the exchanger. Some heat exchangers that use the impingement cooling principal are of the impingement plate type. With such heat exchangers, fluid passes through a plurality of holes in a given plate and strikes a solid portion or "impinges" against a subsequent, usually parallel, plate where it moves along the plate to the nearest orifice and passes through the subsequent plate for impinging against a solid portion of the next plate. Eventually, after passing through a series of plates, the fluid leaves the heat exchanger. This impingement cooling principal aids in the heat transfer between the fluid and each plate. Of course, the holes or orifices in adjacent plates are misaligned intentionally so that the fluid must impinge against a subsequent plate prior to passing through the orifices thereof. This forces the fluid to impinge against each plate after passing through the previous plate to provide a tortuous path for the fluid rather than permitting the fluid merely to flow through holes in a stack of plates.
Some examples of such plate type heat exchangers are shown in U.S. Pat. No. 4,494,171 to Bland et al, dated Jan. 15, 1985 and assigned to the assignee of this invention, as well as other U.S. Pat. No. 4,096,910 to Coffinberry et al, dated June 27, 1978; U.S. Pat. No. 4,347,897 to Sumitomo et al, dated Sept. 7, 1982; and U.S. Pat. No. 4,624,305 to Rojey, dated Nov. 5, 1986.
Most such plate type heat exchangers are designed to exchange heat between fluids which are generally similar. However, there is a need for a new and improved heat exchanger of the character described for accommodating fluids of different characteristics. For instance, it might be desirable to provide different flow paths for fluids of considerably different viscosities, or for one fluid which may be more "dirty" (i.e., containing more particulate matter) than the other. In addition, different fluids can withstand different pressure drops through a heat exchanger such as the impingement plate type. It may desirable to cool an oxidizer using hydrogen as the coolant, and a different pressure drop may be required through one flow path than the other. This invention is directed to a new and improved plate type heat exchanger providing different flow paths for fluids of different characteristics.